Your diabetes team should be helping you slowly reduce your blood sugar levels. Reducing them too fast can cause problems but they do need to come down and, as others have said, you may experience false hypos as they do because your body has got used to them being high.
As for what to eat, with Type 1, your diet does not need to be restricted as insulin is the tool to manage the carbs. Everyone (and I mean “everyone” including people without diabetes) will experience spikes. The important thing is to minimise the time your levels are high with your dose and timing of your insulin.